Union arrays from all object properties

Question

Lets say I have an object:

    let obj={
         hash1:{
            images:[img1,img2....]
         }
         hash2:{
            images:[img100,img200....]
         }  
         hash3:{
             images:[img1000,img2000....]
         }
      ...       
}

I want to union all those arrays in one array. I understand that I can use next code:

let unionArray=[];

Object.values(obj).forEach((item)=>{
unionArray=unionArray.concat(item.images)
});

Are there more elegant way to do such task eg with some framework or in one line coding.

Answer 1

数组约简在这里非常好：

let union = Object.values(obj).reduce((c, i) => c.concat(i.images), []);

Answer 2

You can use map() on Object.keys() and ES6 spread syntax.

 let obj = {"hash1":{"images":["img1","img2"]},"hash2":{"images":["img100","img200"]},"hash3":{"images":["img1000","img2000"]}} var arr = [].concat(...Object.keys(obj).map(e => obj[e].images)); console.log(arr) 

Answer 3

使用Array#map 。

const union = [].concat(...Object.values(obj).map(v => v.images));